Purpose: To evaluate the pattern of choriocapillaris signal voids in maternally inherited diabetes and deafness and in pseudoxanthoma elasticum in eyes before the development of any geographic atrophy.
Methods: The choriocapillaris under the central macula was imaged with the Optovue RTVue XR Avanti using a 10 μm slab thickness. Automatic local thresholding of the resultant raw data extracted areas of absent flow signal, called signal voids, and these were counted and logarithmically binned. The signal void patterns were analyzed in four eyes of two patients with maternally inherited diabetes and deafness and four eyes of three patients with pseudoxanthoma elasticum. None of the patients had geographic atrophy. These data were compared with 55 eyes of 38 healthy control subjects and analyzed with generalized estimating equations.
Results: The choriocapillaris images in maternally inherited diabetes and deafness and pseudoxanthoma elasticum show that the model of signal voids followed a power law distribution, but with a slope and offset much lower than the normal control group, adjusted for age (P < 0.001). The eyes in the disease group were much more likely to have signal voids greater than 40,000 μm.
Conclusion: Before the development of any overt geographic atrophy, patients with maternally inherited diabetes and deafness and pseudoxanthoma elasticum show pronounced abnormalities of choriocapillaris flow. Current clinical measures of retinal pigment epithelial health only look for areas of cell death, as in geographic atrophy. It is not possible to determine from current imaging if the choriocapillaris loss precedes potential loss of function of the retinal pigment epithelium, such as secretion of vascular endothelial growth factor.